Wellheads on TLP platforms can exhibit horizontal offsets due to platform movement. This movement tends to cause the wellheads to be located off of well center. Rigging up coiled tubing onto a wellhead that is not on well center can cause undo stress on the wellhead and/or riser sections extending therefrom. This stress is caused by the wellhead attempting to move back through well center as the platform position or currents change.
Typically, jacking frames are initially positioned on a platform based on the location of the wellhead at that time. This is achieved by physically moving the entire frame into alignment with the instantaneous wellhead position. Such a procedure is time consuming and requires sophisticated and/or large equipment due to the relatively large overall weight of the jacking frame.
In addition, the wellhead is likely to move during a coiled tubing operation, and may not be aligned with the jacking frame after a few hours of operation. An example of such a movement often occurs during a coiled tubing tool change. During a tool change the coiled tubing injector is disengaged from the wellhead. While the wellhead is disengaged from the coiled tubing, it often moves off of well center due to platform movements or currents, among other outside forces. If the wellhead moves off of well center, and a conventional jacking frame is in use, then the jacking frame must again be physically moved into alignment with the wellhead to reconnect the coiled tubing, and its new tool, to the wellhead.
As such, in order to minimize stress on the wellhead and/or riser sections it is desirable for the wellhead to be located on well center, such that when the coiled tubing equipment is disposed over well center, the wellhead and the coiled tubing equipment are in alignment. Accordingly, a need exists for a jacking frame having a centralizer system capable of moving and/or holding a wellhead on well center.